The miniature speaker is an important acoustical component for portable electronic devices, and is used for transforming between electric signal and acoustical signal, and the miniature speaker is an energy converter. Typical miniature speaker usually comprises a housing in which a vibration system and a magnetic circuit system are accommodated. The vibration system comprises a vibrating diaphragm and a vibrating voice coil, wherein the vibrating voice coil is subjected to the acting force of the electromagnetic field and moves up and down according to the polarities of the audio electric signal, thereby enabling the vibrating diaphragm to generate sounds and thus achieving energy transformation between electricity and sound.
Nowadays, more and more old people use hearing aids, however, their hearing aids will squeak and thus become unusable when they are answering calls with telephones equipped with common speakers. Therefore, a hearing-aid voice coil is added into the common speaker by those skilled in the art. Then, audio electric signal is transformed into electromagnetic field through the hearing-aid voice coil, the hearing aid may be switched to such a mode, in which mode the signal is collected by an induction coil in the hearing aid, and the induced signal is amplified and restored into sounds. FIG. 5 illustrates the main structure of a speaker equipped with a hearing-aid voice coil in prior art, which comprises an upper housing 10b and a lower housing 20b combined together, a vibration system and a magnetic circuit system are accommodated in the space defined by the upper housing 10b and the lower housing 20b, and a hearing-aid voice coil 70b is fixed on the lower housing 20b and surrounds the periphery of the magnetic circuit system. However, the miniature speaker with such a structure has a very small space beneath the vibrating diaphragm. Thus, a lead wire of the vibrating voice coil is very easy to contact with the hearing-aid voice coil when the vibrating voice coil vibrates up and down, which makes the higher harmonic of the speaker distort and breaks the lead wire of the vibrating voice coil as well, resulting in defects of the speaker, such as making noise.